1. Field of the Invention
The present invention relates to a cap device having a long connector member, which is linked with a cap on one end thereof
2. Description of the Related Art
In a fuel tank of a vehicle, a known structure to prevent a fuel cap from being missed at the time of fuel supply uses a long connector member like a tether to link the fuel cap with a periphery of a fuel inlet of the fuel tank. One example of such a fuel cap with a tether is disclosed in JP No. 2002-12044A.
As shown in FIG. 38, a fuel cap 200 has a cover 204 with a handle 204a, which is mounted on an upper portion of a casing body 202 in a freely rotatable manner. A tether mechanism 210 is attached to a circumference of a side wall 204b of the cover 204. The tether mechanism 210 includes a rotation ring 212 that is attached to the side wall 204b in a freely rotatable manner, an interlocking ring 213 that supports the rotation ring 212 on the side wall 204b, and a long plate member 214 that is fixed to the rotation ring 212 on one end thereof. The other end of the long plate member 214 is fixed to a fuel lid (not shown). At the time of fuel supply, the fuel cap 200 detached from a fuel inlet is hung from the fuel lid via the tether mechanism 210. This structure prevents the fuel cap 200 from being missed during the fuel supply.
The cover 204 is composed of a resin material having a high water absorbing property (a low swelling resistance), such as polyamide, while the rotation ring 212 of the tether mechanism 210 is composed of a thermoplastic elastomer (TPEE) or a resin material having a relatively low water absorbing property (a high swelling resistance), such as polypropylene. If the cover 204 and the rotation ring 212 are wet with rainwater, the difference in swelling resistance between the cover 204 and the rotation ring 212 narrows the gap between the cover 204 and the rotation ring 212. This undesirably lowers the rotating performance of the rotation ring 212 and may cause a trouble in rotating operations of the fuel cap 200.